Passive steering for a three piece railway truck

ABSTRACT

The present invention opens the side frame pedestal jaws to allow the wheel sets to yaw and align radially to curves. The side frame is supported on wheel sets by elastomeric pads and bearing adapters. The present invention utilizes the elastomeric pad stiffness to compress in pitch motion that allow the wheel set to move in an arc forward or backward in the open jaws of the side frame. The elastomeric pad stiffness also allows the wheelset to twist the pads allowing the wheelset to radially align to the curve. The pads elastic stiffness is sufficient to return when the wheelset is align to straight track.

BACKGROUND OF THE INVENTION

The traditional three piece railway freight truck consists of onebolster and two side frames. The bolster which carries the car bodyextends centrally through the side frames. The bolster is supported by asuspension consisting of springs that support the bolster and frictionshoes with springs that create damping on vertical bolster movement. Thesuspension is centrally located and supported by the side frame. Theside frames ends have pedestal jaws that support on and capture thebearing adapters. The bearing adapters are supported on the wheelsetaxle bearings. The wheel set consists of a live axle with wheels andbearings at the ends.

The truck steering mechanism consists of tapered cone wheel treads. Whenthe truck enters a curve, the rail turns out from under the center ofthe wheel treads. As the rail moves out from under the center of thewheel tread, the tapered cone changes each wheel's diameter and thecircumference of the wheel on the outside of the curve becomes largerand the wheel to the inside of the curve circumference become smaller.The distance the wheels roll down the rail becomes uneven which yaws thewheelset and attempts to radially align the wheel sets to the curve.

The traditional three piece railway freight truck may prevent the wheelsets from achieving radial alignment to curves due to the rigid sideframes acting to restrain the wheelsets from aligning with a curve inthe rails. The side frames also may constrain the wheelset from radialaligning to curves by the limited gap of 0.144 inches on either side ofwheelset axle bearing and the side frame pedestal jaws.

The present invention opens the side frame pedestal jaws to 0.331 incheson either side of wheelset axle bearing and the side frame pedestal jawsto allow the wheel sets to yaw and align radially to curves. The sideframe is supported on wheel sets by elastomeric pads and bearingadapters. The present invention utilizes the stiffness of theelastomeric pad to allow the adapters to pitch and twist in the openjaws of the pedestal. The adapter pitch motion is what allows the wheelset to move in an arc forward or backward in the open pedestal jaws ofthe side frame. The elastomeric pad also allows the wheelset to twistthe pads allowing the wheelset to radially align to the curve. The padselastic stiffness is sufficient to return when the wheelset is align tostraight track.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 is a perspective view of a traditional three piece railwayfreight car truck assembly of a passive steering three piece railway cartruck in accordance with a first embodiment of the present invention;

FIG. 2 is a detailed exploded partial view of the relationship the padand adapter to the side frame and wheel set of the passive steeringthree piece railway car truck in accordance with a first embodiment ofthe present invention;

FIG. 3 is a top view of a railway car truck in a curve with the adaptersalso shown as pitched in separate side views, of the passive steeringthree piece railway car truck in accordance with a first embodiment ofthe present invention;

FIGS. 4A-4D are detailed sectional views of a yawed railway car truckwheel set with the relationship between pitch and yaw of the adapter onthe elastomeric adapter pad, of the passive steering three piece railwaytruck in accordance with a first embodiment of the present invention.

FIGS. 5A and 5B are detailed sectional views of a Pitched and twistedadapter compressing the elastomeric adapter pad, of the passive steeringthree piece railway truck in accordance with a first embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, is a perspective view of a traditional threepiece railway freight car truck assembly 1 is seen to be comprised oftwo laterally spaced side frames 3 between which bolster 4 laterallyextends. Bolster 4 is seen to extend through a central opening in eachside frame 3. Suspension 5, usually comprised of a coil spring group, isseen to support the bolster 4. The side frames 7 are supported at thepedestals 14 by adapter pad 6 and adapter 7 setting on axle bearing 8 ofthe wheelsets 2. The wheelset 2 consists of two wheels 10 pressed onto ajournal portion near ends of an axle 9. The wheelset 2 has axle bearings8 mounted at both ends of axle 9. Adapter pads 6 are typically comprisedof a structural elastomer such as Urethane.

Referring now to FIG. 2, is a detailed exploded partial view of therelationship the elastomeric adapter pad 6 and adapter 7 to side frame 3at the pedestal 14. The adapter 7 is seated on bearing 8. The end ofwheel set 2 is shown with wheel 10 on axle 9. The wheel 10 has a tread16 that is outwardly tapered in a cone shape. Sideframe pedestal openingis formed by depending jaws 12 and pedestal roof 15. The inside surfaceof jaws 12 may include lugs 13 to help position and hold adapter 7.Elastomeric adapter pad 6 vertically captured between the adapter 7 topsurface 26 and the pedestal roof 15. The Legs 27 of the elastomericadapter pad 6 are laterally captured between the lugs 13 and the adapter7.

Referring now to FIG. 3, is a top view, with a side views of eachpedestal 14 and wheel, of a railway car truck 1 in a curve 11 with theadapters 7 pitched 22 and 23. When the railway car truck 1 enters acurve 11, the rail turns out from under the center of the wheel treads16. As the rail moves out from under the center of the wheel tread, 16the tapered cone essentially changes the wheel's diameter with regard tothe center axle-rail distance such that the circumference 17 of thewheel on the outside of the curve becomes larger and the wheel to theinside of the curve circumference 18 becomes smaller. The distance thewheels roll down the rail becomes uneven which yaws 19 the wheelset 2and aligns the wheel sets 2 to the curve 11. The side frame 3 at thepedestals 14 have open jaws 12 to allow the wheel sets 2 yaw 19. Theelastomeric adapter pads 6 become unevenly vertically loaded as thewheel set 2 yaws 19 on adapter 7. The uneven vertical loading compressesthe elastomeric adapter pad 6 at one end more than the other. This actsto pitch the adapter in 22 for the inside of the curve 11 and pitch theadapter out 23 for the outside of the curve 11.

FIGS. 4A-4D show detailed sections of a yawed wheel set 2 with therelationship between pitch 22 and 23 and twist 24 and 25 of theelastomeric adapter pad 6 on adapter 7. The wheel set 2 supports theadapter 7 and the elastomeric adapter pad 6 on the pedestal roof 15 ofthe side frame 3. The vertical load on the elastomeric adapter pad 6 isevenly distributed when the wheel set 2 is rolling on straight track.When the wheel set 2 is yawed in curves the vertical load on theelastomeric adapter pad 6 becomes uneven and the adapter pitches 22 and23. As the adapter pitch as shown at 22 and 23 the adapters also twiston the elastomeric adapter pad 6. The twisted 23 and 24 adapter 7 isconstrained by lugs 13 in the top of the open jaws 12. Each adapter 7and adapter pad 6 is received in one of the sideframe pedestal endsformed by jaws 12. Each adapter pad 6 has a resistance to pitch andtwist such that a longitudinal steering force created between the wheelsto rails of a wheelset of from 5,000 to 7,000 pounds is sufficient toradially align the wheelset with a curve of up to 10 degrees in arailway track. Further, jaws 12 are open enough to allow suchdeformation of the adapter pads 6 to allow the wheel set to yaw to alignwith the curve in the railway track. The pedestal jaws 12 are opened0.331 inches on either side of the bearing to allow space for theadapter 7 to pitch and twist against adapter pad 6. The open jaws 12 issufficient for wheelset 2 to radial align to a 10 degrees in the railwaytrack curve.

FIGS. 5A and 5B show detailed sectional views of a Pitched 23 andtwisted 25 adapter 7 compressing the elastomeric adapter pad 6. Theyawed wheelset bearing 8 creates longitudinal force about the bearing 8.The longitudinal force creates a moment about the top surface 26 ofadapter 7. The longitudinal force and displacement of bearing 8 causethe adapter 7 to compress the elastomeric adapter pad 6 unevenly in thedirection of the displacement. The uneven vertical displacement of theelastomeric adapter pad 6 pitches the adapter 7 and bearing 8. Bearing 8is also yawing as it is displaced. The adapter 7 sitting on bearing 8 isforced to accommodate the yawing motion. Adapter 7 twist 25 theelastomeric adapter pad 6 and compress the elastomeric adapter pad 6legs 27 against lugs 13 to allow the yawing motion.

What is claimed is:
 1. A railway car truck comprising a bolster and twoparallel sideframes, the bolster having two ends each received in anopening in one of the sideframes, a spring group supporting the bolsterend in each sideframe, each sideframe having two pedestal ends, twoaxles each having two ends, two wheels each fitted to a journal portionof each axle, a plurality of axle bearings each fitted on one of theaxle ends, a plurality of adapters each with an adapter pad, with eachadapter and adapter pad received in one of the sideframe pedestal ends,wherein each adapter pad has a resistance to pitch and twist such that alongitudinal steering force created between the wheels to rails of awheelset of from 5,000 to 7,000 pounds is sufficient to radially alignthe wheelset with a curve in a railway track.
 2. The railway cart truckof claim 1 wherein the sideframe pedestal end is comprised oflongitudinally spaced jaws that allow the adapter pad to deform to allowthe wheel set to yaw to align with the curve in the railway track. 3.The railway car truck of claim 2 wherein the adapter pad will deformenough to allow the wheel set to yaw to align with a curve of up to 10degrees in the railway track curve.
 4. A railway car truck comprising abolster and two parallel sideframes, the bolster having two ends eachreceived in an opening in one of the sideframes, a spring groupsupporting the bolster end in each sideframe, each sideframe having twopedestal ends, two axles each having two ends and two journal portions,a wheel fitted to a journal portion of each axle, a plurality of axlebearings each fitted on one of the axle ends, a plurality of adapterseach with an elastomeric adapter pad, with each adapter and elastomericadapter pad received in one of the sideframe pedestal ends, wherein eachadapter pad has a resistance to pitch and twist such that a longitudinalsteering force created between the wheels to rails of a wheelset of from5,000 to 7,000 pounds is sufficient to radially align the wheelset witha curve in a railway track.
 5. The railway cart truck of claim 4 whereinthe sideframe pedestal end is comprised of longitudinally spaced jawsthat allow the adapter pad to deform to allow the wheel set to yaw toalign with the curve in the railway track.
 6. The railway car truck ofclaim 5 wherein the adapter pad will deform enough to allow the wheelset to yaw to align with a curve of up to 10 degrees in the railwaytrack.
 7. The railway cart truck of claim 4 wherein the sideframepedestal jaws that are opened 0.331 inches on either side of the bearingto allow the adapter pad to deform to allow the wheel set to yaw toalign with the curve in the railway track.